Ear clip for medical monitoring device

ABSTRACT

A hinge pin joint for facilitating precise separation of the jaws of a spring clip, comprising: a base cylinder with a threaded bore; supports extending laterally out from said base cylinder; pin supports having means for pivoting; and stabilizing wings extending from the pin supports. In one embodiment, the means for pivoting includes pins that are integral with the pin supports and which extend out laterally from the pin support. An alternate embodiment comprises aligned openings in the pin supports into which pins may be inserted. At least one stopper may be disposed on at least one of the pin supports for supporting the upper shell. The stabilizing wings are configured as plates that are semi-rigidly secured in guide structures within the lower shell.

BACKGROUND

This invention relates to medical diagnosis, and more particularly, toan car clip that allows a medical measuring device to be attached to anear lobe.

Modern medicine today is driven by miniaturization and non-invasive andminimally invasive methods for surgery, examination, diagnosis andand/or monitoring. There is a desire to make examination and treatmentfaster and cheaper. The use of non-invasive techniques reduces pain forthe patient and reduces risk of infection.

Patient monitoring is a key aspect of modern medicine. Monitors ofdifferent types are available for monitoring different body functionsand parameters. Such monitors interact with the body to receive and dataconcerning the body functions for processing.

Blood monitoring devices are conveniently affixed to the earlobe. Mosttypically this is accomplished with a clip. This clip may be a type ofspring clip, wherein the jaws of the clip are forced together by aspring to attach to the earlobe. When levers of extending from the twojaws past an axle are pinched together, the jaws may be separated,thereby releasing the ear lobe, so that the clip can be removed. Whenpressure forcing these levers together is released, the spring draws thejaws together, to grip the earlobe.

A problem with this basic clip design is that the separation between theclosed jaws is not precisely determined. Consequently, the basic clip isnot suitable for applications which require a precisely determined jawseparation. Furthermore, if the pressure is too tight, it may flattencapillaries and adversely affect the blood flow and other blood relatedparameters that are being monitored. A clip should firmly engage theear-lobe without squeezing it sufficiently to affect the readings.

Many non-invasive medical monitoring devices need to be reliablyattached to the body so that accurate readings may be taken. Thesedevices sometimes need to be adjusted to the individual body.

In the case of devices that are attached to the earlobe, some devicesrequire that the distance between the sensing elements be adapted to theindividual thickness of the earlobe of the patient. Such devices arealso required to easily open and close for attaching and releasing theclip from the ear lobe. For diagnostic reliability, the manufacturingtolerances are high, and parts have to be manufactured to highprecision.

With moving parts, particularly where several different independentmovements take place at the same time in a small device and the requiredprecision is very high, for example ±5 microns in position, whilstmaintaining jaw parallelism common production standards of around 100microns are insufficient. Thus, for accurate measurements, there is aneed for a reliable ear clip that can be accurately fitted to apatient's ear lobe with a known but adjustable jaw separation. Such aclip is required to be reliable and easily mass produced.

SUMMARY OF THE INVENTION

A first aspect of the invention is directed to providing a clipcomprising: an upper shell and a lower shell coupled together around ahinge pin, the upper and lower shells having a pair of jaws on a firstside of the hinge pin and handles for squeezing together to separate thejaws on a second side of the hinge pin; a biasing spring to oppose thesqueezing together of the handles and to urge the jaws together and atleast one stop to prevent the jaws from closing completely and to keepthe jaws in parallel alignment when no force is applied to handles toovercome the biasing force of the spring and an adjustment mechanism toadjust the separation of the jaws.

Preferably, the adjustment mechanism comprises an adjustment screw, awasher clip, and an insert; said adjustment screw having a screw headand a threaded shank, the shank being pushed through a clearance hole inthe lower shell and the adjustment screw being held in place around thelower shell by the washer clip, the insert for fitting into a recess inthe upper shell; said hinge pin being attached to said insert; saidinsert comprising a central block with a tapped hole therein, radialarms extending from the central block, and stabilizing wings integrallycast with the central block and radial arms; the stabilizing wings at anangle to the radial arms; said stabilizing wings for engaging the uppershell in accurate alignment with the lower shell; wherein the tappedhole is for receiving the adjustment screw such that the tapped hole andadjustment screw enables adjustment of the separation between the jawsof the upper shell and the lower shell when biasing effect of thebiasing spring is not opposed by a squeezing pressure on handles.

Typically, the clip is for clipping onto an ear lobe.

The clip typically further comprises blood parameter sensors mounted insaid jaws.

Optionally, the stabilizing wings are plates that have an axis that isparallel to an axis of the screw.

Optionally, the stabilizing wings converge slightly towards an axismutually perpendicular to the axes of the hinge pin and the axis of theadjustment screw.

In one embodiment, the hinge pin is integral to the insert.

In an alternative embodiment, the hinge pin engages holes in said insertand holes in said upper shell to connect said upper shell to saidinsert.

Optionally, the stop is a part of the insert.

In an alternative embodiment, the stop is part of the lower shell.

In one embodiment, the biasing spring is a helical spring and ends ofsaid biasing spring bear against the back of the pin supports and middlesection of said spring bears against an inner surface of said uppershell to urge jaws together.

In another embodiment, the biasing spring is wrapped around said hingepin.

A second aspect is directed to an adjustment mechanism for a clipcomprising two shells coupled by a hinge pin, for adjusting a separationbetween jaws of said clip when biased towards each other by a spring,the adjustment mechanism comprising a screw threaded through and lockedto one shell and an insert attached to a second shell having a threadedbore for engaging said screw.

Optionally, the insert comprises stabilizing wings that are parallel tosaid bore and separated from the bore by radial arms, and where thestabilizing wings are restrained by corresponding socket slots in saidshell.

In one embodiment, the screw is locked to one shell with a washer clipthat slides onto and springingly engages shank of said screw.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention, its operating and specificobjects attained by its uses, references should be had to accompanyingdrawings and descriptive matter in which there are illustrated preferredembodiments of the invention.

The invention will now be described in connection with certain preferredembodiments with reference to the following illustrative figures so thatit may be more fully understood.

FIG. 1 is a perspective view of the ear clip in a closed configuration.

FIG. 2 is a perspective view of the ear clip from the angle of FIG. 1,but with the two shells at maximum separation.

FIG. 3 is a top perspective view of one embodiment of the hinge pinjoint.

FIG. 4 is a bottom perspective view of the embodiment of FIG. 3.

FIG. 5 is a rear perspective view of the embodiment of FIG. 3.

FIG. 6 is a perspective view of the adjustment screw with a retainingwasher.

FIG. 7 is a perspective view of the inside of the lower shell of theclip from above, with upper shell and lower cover removed, showing thehinge pin joint and the adjustment screw.

FIG. 8 is a perspective view from the angle of FIG. 7, showing the lowershell of the clip with the upper shell removed, and showing the hingepin joint of FIG. 3-5 but with the adjustment screw of FIG. 6 fullyclosed by being fully threaded into the hinge pin joint.

FIG. 9 is a cut away perspective view from the viewing angle of FIG. 1.

FIG. 10 is a view from the angle of FIG. 9, but showing the ends of theclip closer together.

FIG. 11 is a view from the angle of FIGS. 1, 9 and 10, with the handlessqueezed together and the jaws separated.

FIG. 12 is a side perspective view, of the lower shell and a secondembodiment of the hinge pin joint from above.

FIG. 13 is an enlarged perspective view of the upper shell from below.

FIG. 14 is an end view, showing one embodiment of the biasing spring.

FIG. 15 is a perspective view of a preferred embodiment of the hinge pinjoint mounted on an insert of the lower shell.

FIG. 16 is a perspective view of the preferred embodiment of the hingepin joint.

FIG. 17 is an exploded perspective view of a preferred embodiment of thelower shell, its cover and the hinge pin joint of the preferredembodiment;

FIG. 18 is a perspective view of the under surface of the upper shell.

FIG. 19 is a perspective view of the insert of the lower shell.

FIG. 20 is a perspective view of the under surface of the lower shell.

FIG. 21 is an end view, showing the preferred embodiment of the biasingspring, where for purposes of illustration, the spring has three turns.

FIG. 22 is a schematic illustration of an ear clip of the inventionclipped onto a patient's earlobe.

Consistent numbering is generally used in the various images andembodiments.

DETAILED DESCRIPTION OF THE INVENTION

In the following detailed description, numerous specific details are setforth in order to provide a thorough understanding of the invention.However, it will be understood by those skilled in the art that thepresent invention may be practiced without these specific details. Inother instances, well-known methods, procedures, and components have notbeen described in detail so as not to obscure the present invention.

An advantage of the clip of the invention is that it achieves highprecision within a small mechanical size.

A main feature is that the jaws of the clip do not close together suchthat they touch, but rather close such that they are parallel andseparated by a known gap.

Preferably the gap is adjustable by an adjusting mechanism so that itcan be configured to engage a tissue of a patient, such as an ear lobe,for example.

Other objects, features and advantages of the present invention willbecome apparent upon reading the following detailed description inconjunction with the drawings and the claims.

An embodiment of the invention relates to an ear clip whose ear lobeengaging jaws may be opened around an axis, and whose jaw separation maybe controlled with high accuracy and precision. This is accomplished byan insert having a v-shaped cross section that fits into a guideassembly.

An aspect of the invention is directed to a hinge pin joint comprising:a base cylinder with a threaded bore; supports extending laterally outfrom said base cylinder; pin supports having means for pivoting; andwings extending from said supports. In the preferred embodiment, themeans for pivoting includes pins made integral with the pin supports andextending out laterally. An alternate embodiment includes alignedopenings in the pin supports into which pins are inserted. At least onestopper may be disposed on at least one of the pin supports and thestopper helps to support an upper shell. The support wings may beconfigured as plates that are semi-rigidly secured in guide structuresin a lower shell.

An embodiment of the invention is directed to a clip comprising upperand lower shells that are affixable to a body. The clip comprises ahinge pin joint that includes a base cylinder with a threaded bore;supports extending laterally out from said base cylinder; pin supportshaving means for pivoting; and wings extending from said supports andsemi-rigidly positioned in a cavity of the lower shell. In a preferredembodiment, the means for pivoting includes pins that are an integralpart of the pin supports and extend laterally from the pin supports. Analternate embodiment includes aligned openings in the pin supports intowhich hinge pins are inserted. Distal ends of the hinge pin are securedwithin mountings on the upper shell. An adjustment screw is secured tothe lower shell and threaded into a bore within the base cylinder. Atleast one stopper may be disposed on at least one of the pin supportsfor supporting the upper shell. The support wings are configured asplates that are semi-rigidly secured in guide structures within thelower shell.

This ear clip is a spring clamp that consists of a pair of jaws that maybe opened by a squeezing action on handles that server as levers. Theear clip comprises two sections that each consist a jaw and a handle.The two sections are joined together such that they may pivot, by anaxle pin. The clip further comprises a spring that operates on the hingeand serves to urge the jaws together. Pressure on the handles separatesthe jaws.

The hinge is positioned so that jaws in front of the hinge are separatedwhen the parts of the ear clip behind the hinge (the handles) arepressed. A spring is positioned to keep the ear clip in a closedposition by urging the jaws together and the handles apart. To preventthe ear clip from closing completely, a simple stopper or stoppingmechanism is built into the design. The stopper allows the ear clip toclose in such a manner that the jaws (the sides of the ear clip that areon the ear lobe) are parallel to each other about the ear lobe at allseparations to be measured between the sensors. This is in contrast toknown clips, wherein the jaws tilt towards each other and meet at a linewhen fully closed, such that, for each jaw separation, the angle of thejaws is different, and the jaws slope. The jaws of the clip of thepresent invention are parallel to each other and may be fastened aroundan ear lobe.

The two parts of the ear clip can be adjusted with respect to each otherso that, when they are in a closed position, the distance between thetwo parallel jaws can be set to a known desired separation (either moreor less), in order to fit to the thickness of a specific patient'searlobe.

This arrangement allows positioning a number of sensors in the tips ofeach half such that they remain parallel to each other. Otherwise, thejaws would close to an unknown separation that depends on the individualthickness of the ear lobe and the strength of the spring, and, insteadof being parallel, the jaws and sensors therein would be at an angle.Even when a stop is used that prevents the two halves from closingcompletely, it is possible that a thicker than usual ear lobe will notallow the two halves to close until they reach in their closing movementthe stop, thus also leading to a situation where the sensors on the twohalves are not exactly parallel to each other, but instead are at asmall angle. The consequence of such angled sensors would lead todifferences of measurement due to differences of relative positions ofthe sensors, depending on each patient's individual earlobe.

The two halves of the device are hollow and also serve as the housingfor the electronic components, and hold the base of the sensors and anadjustment mechanism.

According to the invention, the hinge pin coupling the two parts ismounted on a separate component that is connected to a dedicatedadjustment mechanism that is typically a screw that allows theadjustment of the separation between the sensors at the tip of the clipin a closed position and also allows the two halves of the clip to beopened when the handles are pressed and closed by the spring when thehandles are released.

A difficulty in clip construction of an ear clip for monitoring bloodparameters of blood vessels in the ear lobe is that manufacturingclearances are needed to allow the clip to be opened and closed. Keepingthe necessary minimum clearance between moving parts, however, leads toless precision concerning the exact parallelism and position of thesensors in the tip end (jaws) of the clip. Because the sensors arepositioned in the jaws of the clip, inaccuracies resulting from therequired clearance in the middle section of the clip (i.e. around theaxle) that is necessary for the movement of the parts is magnified asone moves from the axle towards the jaws and results in a biggerinaccuracy in the jaws where the sensors are mounted.

In addition to the necessary clearance to allow movement, manufacturinginaccuracies may lead to a further decrease of precision. Suchmanufacturing inaccuracies may lead to parts that fit together tootightly to be easily moved, or that are too loose to maintain thenecessary precision and parallelism for holding sensors.

Thus there is a need to allow the jaws to be opened and closed easily,whilst nevertheless enabling accurate control of the separation of thejaws.

These problems of clearances, accuracy and precision during productionare overcome by the introduction of specially formed male and femaleparts. These specially formed parts compensate for the requiredtolerances and manufacturing inaccuracies, whilst achieving the desiredjaw separation precision.

Referring now to FIGS. 1 and 2 an ear clip 5 is shown. The ear clip 5includes lower and upper shells 10, 12 in which various sensorcomponents are housed. As will be hereinafter explained, the shells 10,12 pivot with respect to each. This pivoting action allows jaws 20 atthe ends of the shells to be separated to facilitate placement on theearlobe.

If desired, the surfaces of the shells 10, 12 may include non-slip pads6, perhaps with a texture, to facilitate gripping.

The shells 10, 12 may be fabricated from a wide range of suitablematerials. In preferred embodiments, the shells 10, 12 fabricated fromplastic and, may be injection moulded, for example.

A number of sensors may be positioned within the jaws 20 of the shells10, 12, depending on the parameters to be monitored or measured. In oneimplementation, the ear clip 5 is used for non-invasively measuringglucose in the blood stream and appropriate sensing elements arerequired. Details of appropriate sensors may be found in issued U.S.Pat. No. 8,235,897, co-pending USA patent application Ser. No.13/540,656 and International application PCT/IL2001/000328). In thisimplementation, a thermal sensor 14 for the thermal measuring channel islocated on the tip 16 of one of the shells in the drawing it is in onthe lower shell 10, it may, however, 1 and 2 contain it placed on thelower shell) of the ear clip 5. Membranes 18 may also be provided. Thesemembranes 18 serve to house piezzo electrical transducers (such as atransmitter and a receiver) for an ultrasonic measuring channel, forexample. The membranes 18 may also serve as capacitor plates for anelectromagnetic measurement channel, for example.

The specific sensors and monitoring elements are, however, not pertinentto the invention that is described and claimed herein. Any desirablecombination of sensors and monitoring elements may be utilized in theear clip 5. Sensor 14 and sensor 18 shown and described are forillustrative purposes only. Any suitable support structure may beutilized in the shells for the electronic components.

It will be appreciated that depending on the sensors and monitoringelements that are used and the accuracy of measurement required, certainparameters and orientations need to be maintained for proper andaccurate operation of the car clip 5 as a tool for measuring bloodparameters. In particular, for the aforementioned non-invasive glucosemonitor, the membranes 18 need to be oriented precisely with respect toeach other in order to obtain accurate readings. The separation d of themembranes 18 around the earlobe to which the ear clip 5 is attached mustbe accurately determined and maintained in order for the readings to beaccurate and to avoid recalibration, and the membranes 18 must be fullyparallel.

A simple spring clip that closes onto the ear lobe under influence of aspring, whose separation is determined by the thickness of the ear lobeand the strength of the spring, will have a varying separation and willnot generate reproducible results. It is thus necessary to separate theearlobe engaging and clasping effect of the spring that enables the clipto be engaged on the ear lobe, and a separate means of controlling theseparation of the jaws 20 when no external separating force is acting,and the jaws 20 of the clip 5 are attached onto the ear lobe by thespring.

FIG. 1 shows one position of the herein ear clip 5 wherein the jaws 20of the shells 10, 12 are close together thereby bringing the membranes18 into close proximity d, where the membranes 18 are in parallel witheach other and are separated by a known and controllable gap. Typically,this is the operational position when the clip 5 is affixed on theearlobe of a subject. FIG. 2 shows the ear clip 5 in another positionwhere the jaws 20 of the shells 10, 12 are separated by a larger gap.This would be the position, wherein the jaws 20 of the shells 10, 12 aresufficiently separated that the ear clip 5 may be attached to a thickerearlobe. The gap between the jaws may be varied over a range, typicallyof from about 3 mm to about 6 mm.

The gap may be controlled by an adjustment mechanism that includes ascrew 38 that engages a hinge pin joint 22.

One embodiment of the hinge pin joint 22 is illustrated in FIGS. 3-5. Asecond, preferred embodiment of the hinge pin joint 122 is illustratedin FIGS. 15-21. The hinge pin joint 22 (122) together with theadjustment screw 38 shown in FIG. 6 allow precise separation of the jaws20 of the shells 10, 12 and their precise, parallel alignment withrespect to each other.

The upper shell 12 may pivot around an axle pin 50. The axle pin 50 is acentral element, which allows precise pivoting of the shells 10, 12 withrespect to each other so that the jaws 20 may be separated to allow theclip 5 to be securely attached to an ear lobe.

With reference to FIGS. 3 to 5, in a first embodiment, the hinge pinjoint 22 includes a base cylinder 24 with a threaded bore 26. Extendingradially from the base cylinder 24 are radial arms 28. Pin supports 30are affixed to the radial arms 28. The pin supports 30 have aligned axlebearing holes 32 for engaging an axle pin 50 (FIG. 12). The ear clip 5includes a stop 34 that prevents the jaws from closing together beyond aparallel alignment. As shown in FIGS. 3-5, in one embodiment, the stop34 may be part of a pin support. At the end of each radial arm 28,stabilizing wings 36 are provided. Preferably, the stabilizing wings 36extend at an angle of more than 45° to the radial extensions 28. Morepreferably, the stabilizing wings 36 extend at an angle of 70° to 110°and, most preferably, the stabilizing wings 36 are approximatelyperpendicular to the radial extensions 28. In preferred embodiments,these wings 36 are plate-like, but in alternative embodiments, the wingsmay be rods or may any other useful and desirable shape. The stabilizingwings 36 may extend both forwards and backwards from the radial arms 28,and tightly fit into a correspondingly shaped housing within theinjection moulded lower shell 10. In this manner, a tight fit isachievable using the ordinary tolerances for injection moulding, therebyenabling accurate alignment between the sensor components attached tothe upper 12 and lower 11 shells.

With reference to FIG. 16, in a preferred embodiment, the hinge pinjoint 122 includes a base cylinder 124 with a threaded bore 126.Extending radially from two sides of the base cylinder 124 are radialextensions 128. Pin supports 130 are provided on the radial extensions128. In one embodiment, the pin supports 130 may include integral hingepins 133. On one of the pin supports 130, a stop 135 is placed. At theend of each radial extension 28, support wings 136 are provided. In apreferred embodiment, the support wings 136 are plates, but in otherembodiments, the support wings 136 may be rods or may assume some otheruseful and desirable shape.

In preferred embodiments, the adjustment means comprise an adjustmentscrew 138 as shown in FIG. 20 that screwingly engages the threaded bore26, 126. Preferably, for attachment to an ear lobe, the step of thethread is 0.5 mm. For other embodiments, such as for other applications,other thread steps may be selected, depending on the size of the clip.The adjustment screw 138 has a threaded shank 40, 140 and an enlargedhead 42 with a slot 48 for a screw driver, which may be a conventionalslot or cross, a hexagonal head or a unique slot for a dedicated tool.The head 42 of the screw is typically counter sunk into the shell. Tohold the screw 38 in place within the lower shell 10, a retaining washerclip 46, 149 may be used. The retaining washer 46, 149 is an open clipthat slides onto the threaded shank of the adjustment screw 38. It maybe fabricated from metal, for example.

An alternate embodiment of the adjustment screw 38 is shown in FIG. 6.It is a standard screw 38 with a threaded shank 40 and an enlarged head42 with a slot 48 therein for a tool or key.

FIGS. 15-18 show the hinge pin joint 122 fitted into an insert 109 ofthe lower shell 10. The adjustment screw 38 is inserted through anopening in the lower shell 110 and is threaded into the lower end of thethreaded bore 126 of the base cylinder 124. The adjusting screw ispositioned so that the working ends (jaws) 20 of the upper and lowershells 10, 12 of the clip 5 are at an appropriate separation to engage apatient's ear lobe securely enough for the clip 5 to be clipped inplace, but loosely enough so as not to squash the capillaries of the earlobe. Once calibrated to an appropriate separation, the clip may beopened by pressure to the grips 6, to separate jaws 20, but on releaseof squeezing pressure, the jaws return to parallel alignment at the setseparation. FIG. 11 shows that the clip 5 may be adjusted by theadjusting screw 38 such that the distance between the sensors 18 in thejaws 20 can be increased or decreased. The adjustment screw 38 isprovided with a locking washer 46 just below the head 42.

For an alternative embodiment, FIGS. 7-9 show the hinge pin joint 22fitted into the lower shell 10. The adjustment screw 38 is insertedthrough an opening 47 in the lower shell 10 and is threaded into thelower end of the threaded bore 26 of the base cylinder 24 of the hingepin joint 22 (see FIGS. 1, 9, 10 and 11). The adjusting screw 38 ispositioned (shown in FIG. 10) so that the working ends 20 of the upperand lower shells 12, 10 of the clip are close together. FIG. 9 showsthat the clip 5 may be adjusted by using the adjusting screw 38 in a waythat the separation distance between the sensors is increased.

In the preferred embodiment, the axle pin 133 on the hinge pin joint 22is held by hearings consisting of a socket having one part 135 on thelower cover 109 (FIGS. 15, 19), and a second part 137 on the upper shell112 (FIG. 18) that close around the pin 133 to hold it tightly in placeso that the upper and lower shells 10, 12 are held together by the pin133. In this manner the upper shell 112 pivots about the pin 133 andpivots with respect to the lower shell 110.

In connection with the embodiment shown in FIG. 12, an axle pin 50 maybe inserted into the aligned openings 32 of the pin supports 30 of thehinge pin joint 22. The ends of the axle pin 50 are engaged by holes inmountings 52 on the upper shell 12 (see FIG. 13). In this manner theupper shell 12 may be pivoted about the axle pin 50 with respect to thelower shell 10.

A biasing spring 54 may be used to maintain the shells 10, 12 in aclosed position. In one embodiment, shown in FIGS. 14 and 21, the ends56 of the biasing spring 54 exert a force against the back of the pinsupports 30 and the central portion (or bow) 58 of the spring 54 exertsa force against the inner surface of the upper shell 12. (FIG. 21) Bypressing on the handle ends 11 of the shells 10 and 12, the resistiveforce of the spring 54 is overcome, and the working ends (jaws) 20 ofthe shells 10 and 12 are separated beyond the predefined parallelseparation. When pressure is released, the spring 54 restores theworking ends 20 of the shells back to their predefined position, withthe spacing set by the adjustment means, typically the screw 38. In someembodiments, it may be desirable to provide clips 159 (FIG. 21) toengage and hold the central region (or bow) 58 of the spring 54

In one embodiment, the coiled biasing spring 54 may be wrapped aroundthe hinge pin 50 to maintain the shells 10, 12 in their predeterminedparallel and close position. Ends 56 of the spring bear against the backof the pin supports 30 and the central region (a bow) 58 in the middleof the spring bears against the inner surface of the upper shell 12(FIG. 14). By pressing on the handle ends 11 of the shells 10 and 12,the force of the spring 54 is overcome, and the jaws 20 of the shells 10and 12 are moved apart. When pressure is released, the spring 54restores the working ends or jaws 20 of the shells 10, 12 back to theirpredefined spacing.

As shown in FIG. 7, the hinge pin joint 22 may be situated within anappropriately shaped cavity of the lower shell 10 so that it cannotrotate or wiggle about, but may be moved up and down to some extentwithin the confines of the cavity of the lower shell 10. Guidancestructures 60 are built into the surface of the lower shell 10 tosemi-rigidly hold the hinge pin joint 22 in place, but with sufficientclearance for the hinge pin joint 22 to be able to move relative to thelower shell 10.

By means of the hinge pins 133 (or the pin 50) the hinge pin joint 22(122) is fixedly secured to the upper shell 12 (122) by virtue of theends of the pin(s) being held in the upper shell 12 (122) (either inhinge socket 35 or the mountings 52).

The position of the screw 38 within the threaded bore 26 of the basecylinder 24 of the hinge pin joint may be adjusted with an appropriatescrewdriver for engaging the screw head 48. Optionally, a special screwhead 48 is used, that requires a dedicated screwdriver tool.

Adjustment of the screw 38 moves the hinge pin joint 22 (122) up anddown with respect to the lower shell 10 (110). Since the screw 38 isfixedly positioned in the lower shell 10 (110) by the washer clip 46,and the hinge pin joint 22 (122) is fixedly positioned in the uppershell 12 (112), rotation of the screw 38 within the bore causes verticaldisplacement of the shells 10 (110), 12 (112) relative to each other,and adjusts the separation of the jaws 20. Turning the screw 38clockwise or anticlockwise threads it further into or out from the bore26 of the hinge pin joint 22 and adjusts the separation of the shells 10(110), 12 (112) relative to each other. Hence rotation of the screw 38allows the user to adjust the distance between the jaws 20 of the twoshells 10 (110), 12 (112) (and thus between membranes 18 and othersensors, by increasing or decreasing their separation. This allows aprecise adjustment of the distance between the jaws 20 of the shells 10(110), 12 (112).

The pitch of the thread on the screw 38 is selected precisely so that asingle full turn of the screw 38 translates to a known precise distance.In one embodiment, a 360° turn corresponds to a separation of 0.4 mmbetween the working ends of the shells 10, 12. Therefore, by carefulrotation of the screw, the user may precisely determine the distancebetween the sensors on the working ends (jaws) 20 of the shells 10, 12.It is relatively easy to give a quarter turn, half turn or three quarterturn to the screw to thereby separate the jaws 18 of the shells 10, 12by 100 microns at a time. Smaller turns are also possible. Optionally,the underside of the lower shell 10 is marked so that known smalladjustments may be made more easily and accurately. It will beappreciated that other threads could be utilized, and a single full turnmay be set to other small amounts, such as 0.3 or 0.5 mm etc.

As aforesaid, in some embodiments, extending laterally from the pinsupports 30 of the hinge pin joint 22 are stops 34. These stops 34prevent the jaws 20 from closing completely and keep the jaws, when nosqueezing pressure is applied to the handles 11, in parallel with eachother at a separation controlled by the turning of the screw 28 tomaintain the proper parallel relationship between the upper and lowershells 12, 10 when the clip 5 is closed and in its working position,thereby making the arrangement more stable. A preferred embodiment shownhas one stop 34 on just one of the pin supports 30, but in otherembodiments, two stops may be provided.

The specially formed part (hinge pin joint) 22 includes the threadedbore 24 for the screw 38 that is used to adjust the separation betweenthe working ends or jaws 20 of the shells 10, 12 (and thus the sensors),when handles 11 are released. Stabilizing wings 36, typically formed asplates, function in the guide structure 60 of the lower shell 12. Thesestabilizing wings 36 may be arranged at an angle so that they aredirected to a meeting point along the lateral axis of the clip 5,perpendicular to the hinge pins 33 (50). Alternatively, the stabilizingwings 36 may be strictly parallel to the axis on which the height or thedistance between the sensors is adjusted. Thus, referring to the axis ofthe adjusting screw 38 as the Z axis, and the axis of the hinge pin 50(133) as the y axis, the stabilizing wings 36 (136) are symmetricallyarranged and may converge or be parallel to the x axis that isperpendicular to the z and y axes, thus defined. The stabilizing wings36 (136) are tightly engaged by corresponding slots in the upper shell10 and, by using regular manufacturing tolerances, looseness about thehinge, as is typical of regular clips, is avoided and accurate alignmentof the sensors 18 is enabled. The two stabilizing wings 36 (136) mayform together an interrupted v-shaped form that fits in the guidestructure of the upper shell 12, having the same angle.

An advantage of the stabilizing wings 36 (136) being slightly convergingis that the hinge pin joint 22 (122) will thereby generally adjustitself within the slot of the upper shell 12 to maintain properpositioning despite regular manufacturing tolerances or slightinaccuracies during fabrication. Where, due to production inaccuracies,the parts with the guide structure are wider-than the theoreticaldimension, the hinge pin joint 22 (122) with the two stabilizing wings36 (136) that are arranged in a v-shape would move further towards thetips and would then adjust the part there. If the part with the guidestructure in it is smaller than the theoretical dimension, then the partwith the two stabilizing wings 36 (136) would move a bit away from thetips until it rests at the exact location.

The same true when the part with the two plates is bigger or smallerthan the theoretical dimension. Here also the stabilizing wings 36 (136)would find the exact point, where they fit their socket precisely, bymoving along the x-axis. The amount of movement along the x-axis isdependent on the degree of accuracy of the final part. This angledetermines how much the part would then be out of centre relative to thecentre point of the screw 38 that adjusts the two halves of the clip 5along the z-axis. Inaccuracies along the y-axis are also completelycompensated for with this construction.

It will be appreciated that if the thread 26 for the bore 24 where thescrew 38 is cut in at the end of the assembly process of the clip 5,after the montage, then the thread 26 will always be correctly centred.

The use of plates for the stabilizing wings 36, instead of, for examplefour rods or pins, leads to high accuracy and stability about the axlepin 50 (133). Such plate like stabilizing wings 36 have a maximumcontact surface for their form where the plates are leaning against theguide structure. The maximum contact surface also leads to maximumsupport from the guide structure on the plates. Rods, for example, couldbend into either the direction of the x- or the y-axis. The convergingof the plates stands with the wall of either the right side or the leftside with its complete surface and with a wall that stands with itscross-section against the force or partial vector of this force againstany bending in either x- or y-direction.

Because the two stabilizing wings 36 are on the outside and aredistanced from the adjustment screw 38, they have maximal leverageagainst any bending around the z-axis and/or along the x-axis. It willbe appreciated that possible bending along the y-axis is not usually aproblem because the stop 34 provides additional support to the clip inthis direction. That would mean that the plates have otherwise run alongthe whole length of the clip 5. This bending moment is in the directionof the rotation around the hinge of the two halves of the clip 5 and isless critical, because the stop 34 provides additional support to theclip 5 in this direction.

Because the two stabilizing wings 36 are close to the outer edges of theclip 5 and separated as far as possible from the adjustment screw 38,they require a minimum of additional material for the guide structureand leave a maximum of space for the electronic components to be packedinto the clip 5. The two converging stabilizing wings 36 are connectedto the threaded bore 24 for the adjusting screw 38 by radial arms 28that extend from the threaded bore 24.

The convergence also helps in production where it is generally necessaryto add at least a two degrees angle to help remove parts from theirmolds. The converging shape allows the stabilizing wings 36 to remainstraight, when the parting line is positioned along the y-axis.

With reference to FIG. 22, an ear clip of the invention clipped onto apatient's earlobe is shown.

It will be evident to those skilled in the art that the invention is notlimited to the details of the foregoing illustrative embodiments andthat the present invention may be embodied in other specific formswithout departing from the spirit or essential attributes thereof. Thepresent embodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.

We claim:
 1. A clip comprising: an upper shell and a lower shell,coupled together around a hinge pin, the upper and lower shells having apair of jaws on a first side of the hinge pin, and handles for squeezingtogether to separate the jaws on a second side of the hinge pin; abiasing spring to oppose the squeezing together of the handles and tourge the jaws together; at least one stop to prevent the jaws fromclosing completely and to keep the jaws in parallel alignment when noforce is applied to handles to overcome the biasing force of the spring;and an adjustment mechanism to adjust the separation of the jaws.
 2. Theclip of claim 1, wherein the adjustment mechanism comprises anadjustment screw, a washer clip, and an insert; said adjustment screwcomprising a screw head and a threaded shank, the shank being pushedthrough a clearance hole in the lower shell, the adjustment screw beingheld in place around the lower shell by the washer clip, and the insertfor fitting into a recess in the upper shell, said hinge pin beingattached to said insert; said insert comprising a central block with atapped hole therein, radial arms extending from the central block, andstabilizing wings integrally cast with the central block and radialarms, the stabilizing wings at an angle to the radial arms; saidstabilizing wings for engaging the upper shell in accurate alignmentwith the lower shell; wherein the tapped hole is for receiving theadjustment screw such that the tapped hole and adjustment screw enablesadjustment of the separation between the jaws of the upper shell and thelower shell when biasing effect of the biasing spring is not opposed bya squeezing pressure on handles.
 3. The clip of claim 1, for clippingonto an ear lobe.
 4. The clip of claim 3, further comprising bloodparameter sensors mounted in said jaws.
 5. The clip of claim 2, whereinthe stabilizing wings are plates that have an axis that is parallel toan axis of the screw.
 6. The clip of claim 5, wherein the stabilizingwings converge slightly towards an axis that is mutually perpendicularto the axes of the hinge pin and the axis of the adjustment screw. 7.The clip of claim 1, wherein the hinge pin is integral to the insert. 8.The clip of claim 1, wherein the hinge pin engages holes in said insertand holes in said upper shell to connect said upper shell to saidinsert.
 9. The clip of claim 1, wherein the stop is a part of theinsert.
 10. The clip of claim 1 wherein the stop is part of the lowershell.
 11. The clip according to claim 1 wherein said biasing spring isa helical spring and ends of said biasing spring bear against the backof the pin supports and middle section of said spring bears against aninner surface of said upper shell to urge jaws together.
 12. The clipaccording to claim 1 wherein said biasing spring is wrapped around saidhinge pin.
 13. An adjustment mechanism for a clip comprising two shells,for adjusting a separation between jaws of said clip when biased towardseach other by a spring, the adjustment mechanism comprising a screwthreaded through and locked to one shell and an insert attached to asecond shell having a threaded bore for engaging said screw.
 14. Theadjustment mechanism of claim 13 wherein the insert comprisesstabilizing wings that are parallel to said bore and separated from thebore by radial arms, and where the stabilizing wings are restrained bycorresponding socket slots in said shell.
 15. The adjustment mechanismof claim 13, wherein the screw is locked to one shell with a washer clipthat slides onto and springingly engages shank of said screw.
 16. A clipcomprising: an upper shell and a lower shell, coupled together around ahinge pin, the upper and lower shells having a pair of jaws on a firstside of the hinge pin, and handles for squeezing together to separatethe jaws on a second side of the hinge pin; a biasing spring to opposethe squeezing together of the handles and to urge the jaws together; aninsert for fitting into a recess in the upper shell, said hinge pinbeing attached to said insert, said insert comprising a central blockwith a tapped hole therein, radial arms extending from the centralblock, and stabilizing wings integrally cast with the central block andradial arms, the stabilizing wings at an angle to the radial arms; saidstabilizing wings for engaging the upper shell in accurate alignmentwith the lower shell, wherein the tapped hole is for receiving theadjustment screw such that the tapped hole and adjustment screw enablesadjustment of the separation between the jaws of the upper shell and thelower shell when biasing effect of the biasing spring is not opposed bya squeezing pressure on handles.
 17. An adjustment mechanism for a clipcomprising two shells and jaws biased towards each other by a spring,the adjustment mechanism comprising a screw threaded through and lockedto one shell and an insert attached to a second shell comprising athreaded bore for engaging said screw, stabilizing wings that areparallel to said bore and separated from the bore by radial arms, andwhere the stabilizing wings are restrained by corresponding socket slotsin said shell.